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Formation of trichothecenes by Fusarium solani var. coeruleum and Fusarium sambucinum in potatoes. 总被引:3,自引:3,他引:0
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A A el-Banna P M Scott P Y Lau T Sakuma H W Platt V Campbell 《Applied microbiology》1984,47(5):1169-1171
Fusarium solani var. coeruleum can form deoxynivalenol in potato tubers and in liquid medium, although concentrations observed in the rot were highly variable; acetyldeoxynivalenol and HT-2 toxin were detected in 1 to 3 tubers only (of 57). Trichothecenes were also detected in a very few (3 of 20) cultures of Fusarium sambucinum in potato tubers. 相似文献
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A. R. ENTWISTLE 《The Annals of applied biology》1971,69(3):213-222
The pathogenicities of Phoma exigua var. foveata and P. exigua var. exigua were compared by determining the relationship between incidence of infection of whole tubers or tuber pieces and various inoculum levels in soil. In natural soil var. foveata was more pathogenic than var. exigua, but in sterilized soil there were no clear differences between the two. Both varieties were isolated from some lesions derived from inoculum to which only one variety had been added indicating either natural contamination of soil or latent infection in tubers; the proportion of such lesions increased at the lower inoculum concentrations. In studies where potato plants were grown in infested soils, the incidence of stem disease and tuber disease increased at increased inoculum concentrations of var. foveata; var. exigua was not added to the inoculum but was isolated from some lesions, the proportions of such lesions again increasing at lower inoculum concentrations. The infectivity of the infested soil, assessed by a tuber-baiting method, declined soon after planting but increased prior to harvest. Laboratory studies indicated that in natural soil the infectivity was highest after 2–3 months and lowest after 10 months incubation, but in sterilized soil infectivity was highest after 5 months and lowest after 7 months incubation. 相似文献
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Effects of delaying fungicide treatment of wounded potatoes on the incidence of Fusarium dry rot in store 总被引:1,自引:0,他引:1
Potato tubers artificially inoculated with Fusarium solani var. coeruleum or F. sulphureum 3 months after harvest were uniformly wounded and held at 5, 10 or 15°C for up to 21 days before immersion in fungicide suspensions. Holding tubers for 14 days at 15°C (curing conditions) or at 5°C did not alter the incidence of dry rot subsequently developing on tubers stored at 10°C, and holding tubers for up to 21 days at 15°C slightly increased disease caused by both pathogens. Thiabendazole, imazalil and prochloraz applied to tubers immediately after wounding almost completely prevented dry rot. Treatment after 3 days was less effective and the amount of disease increased with further delay; fungicides were more effective on tubers held at 5°C than at 10 or 15°C before treatment and storage, and efficacy of the fungicide was decreased by increasing the amount of inoculum on tubers. Wounds became less susceptible to infection by F. solani var. coeruleum and F. sulphureum when tubers were held at 15°C before inoculation, and the incidence of rots was decreased by 70–80% by delaying inoculation for 7 days. Treating tubers with dichlorophen immediately after wounding slightly increased the disease. The effects of fungicide treatment, curing conditions and wound healing are discussed. 相似文献
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Fusarium graminearum causes head blight disease in wheat and barley. To help understand the infection process on wheat, we studied global gene expression of F. graminearum in a time series from 24 to 196 h after inoculation, compared with a noninoculated control. The infection was rapid and, after 48 h, over 4,000 fungal genes were expressed. The number of genes expressed increased over time up to 96 h (>8,000 genes), and then declined at the 144- and 192-h post-inoculation time points. After subtraction of genes found expressed on complete medium, during carbon or nitrogen starvation, and on barley, only 355 were found exclusively expressed in wheat, mostly genes with unknown function (72.6%). These genes were mainly found in single-nucleotide polymorphism-enriched islands on the chromosomes, suggesting a higher evolutionary selection pressure. The annotated genes were enriched in functional groups predicted to be involved in allantoin and allantoate transport, detoxification, nitrogen, sulfur and selenium metabolism, secondary metabolism, carbohydrate metabolism, and degradation of polysaccharides and ester compounds. Several putative secreted virulence factors were also found expressed in wheat. 相似文献
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From 1997 to 1999 the occurrence ofFusarium spp. on wheat grain and its contamination with the mycotoxins deoxynivalenol and invalenol were investigated under organic farming conditions in the Rhineland, Germany. For comparison, some trials were also run under integrated farming conditions. The importance of the seed contamination withFusarium spp. as well as the impact of farming system, previous crop and soil preparation on the inoculum sources ofFusarium spp. in the soil were investigated. The data on the inoculum sources was compared to the Fusarium infection of grains and their content of DON and NIV. The crop residues in the soil were the most important inoculum source for the Fusarium species infecting wheat ears and grains. The amount of potential inoculum in the soil largely depended on the previous crop and the system of soil preparation. 相似文献
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In experiments in three years, seed tubers were inoculated before planting with either Fusarium solani var. coeruleum or F. sulphureum to initiate a rot, or were contaminated by dipping in soil slurries containing spore suspensions of one or other of the pathogens. Transmission to progeny tubers was tested by uniformly wounding and incubating tubers and by dilution plating of soil samples. In two years, transmission of F. sulphureum was greater from highly contaminated than from rotting seed and was greater on cv. Pentland Crown than on cvs Desiree and Maris Piper. F. solani var. coeruleum appeared to be transmitted most readily from rotting seed and Maris Piper was the cultivar most extensively contaminated. In experiments with different harvest dates, transmission of both fungi from highly contaminated seed could be detected by late June or mid-July. More progeny tuber wounds rotted in F. sulphureum than in F. solani var. coeruleum plots and in one year, F. sulphureum caused more rots on cv. Record than on cv. Maris Piper. These differences between the pathogens may be related to their differing abilities to sporulate underground on the surface of seed tubers and on stem bases. 相似文献
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Fusarium oxysporum f. sp. vasinfectum penetration hyphae infect living cells in the meristematic zone of cotton (Gossypium barbadense L.) roots. We characterized wall modifications induced by the fungus during infection of the protodermis using antibodies against callose, arabinogalactan-proteins, xyloglucan, pectin, polygalacturonic acid and rhamnogalacturonan I in high-pressure frozen, freeze-substituted root tissue. Using quantitative immunogold labelling we compared the cell walls before and after hyphal contact, cell plates with plasmodesmata during cytokinesis, and wall appositions induced by fungal contact. In the already-existing wall, fungal contact induced only minor modifications such as an increase of xyloglucan epitopes. Wall appositions mostly exhibited epitopes similar to the cell plate except that wall appositions had a much higher callose content. This study shows that wall appositions induced by Fusarium oxysporum hyphae are the result of normal cell wall synthesis and the addition of large amounts of callose. The appositions do not stop fungal growth. 相似文献
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T. Small PhD 《The Annals of applied biology》1945,32(4):310-318
The effect of bruising and of disinfecting ('dipping') seed potatoes with a proprietary organo-mercury preparation on the incidence of dry rot in them was tested in field trials during three seasons. The tubers used were of the susceptible variety Ninetyfold, taken from crops grown in contaminated soil, harvested immature in July to early August each year under farm conditions, and stored in boxes.
Seed tubers not deliberately bruised, whether dipped or not at lifting time, remained practically sound until planting time in the fallowing season, if left undisturbed in their boxes.
Tubers deliberately bruised, either at digging time or 1-2 weeks later, but not dipped, developed severe dry rot with few exceptions. The disease had run its course by mid-October. When undipped, sound tubers were bruised in October, they contracted severe dry rot, but dipping such tubers immediately before bruising reduced the loss satisfactorily in five out of six trials.
Tubers bruised at digging time and immediately dipped suffered little from dry rot in almost all cases. Delayed dipping of bruised tubers checked the disease in some trials but not in others. Seed tubers severely bruised 1-2 weeks after being dipped remained practically sound except in one instance, whereas tubers severely bruised approximately 3 months after being dipped, subsequently developed severe dry rot in four out of six tests, unless they had been redipped immediately before they were bruised.
Inoculation of healthy tubers with soil samples showed that the fungus is widely distributed in potato fields in Cheshire. Dipping killed all, or almost all, of the fungus in the soil adhering to the seed tubers.
The results are discussed and suggestions are made for further investigations and for practical control measures. 相似文献
Seed tubers not deliberately bruised, whether dipped or not at lifting time, remained practically sound until planting time in the fallowing season, if left undisturbed in their boxes.
Tubers deliberately bruised, either at digging time or 1-2 weeks later, but not dipped, developed severe dry rot with few exceptions. The disease had run its course by mid-October. When undipped, sound tubers were bruised in October, they contracted severe dry rot, but dipping such tubers immediately before bruising reduced the loss satisfactorily in five out of six trials.
Tubers bruised at digging time and immediately dipped suffered little from dry rot in almost all cases. Delayed dipping of bruised tubers checked the disease in some trials but not in others. Seed tubers severely bruised 1-2 weeks after being dipped remained practically sound except in one instance, whereas tubers severely bruised approximately 3 months after being dipped, subsequently developed severe dry rot in four out of six tests, unless they had been redipped immediately before they were bruised.
Inoculation of healthy tubers with soil samples showed that the fungus is widely distributed in potato fields in Cheshire. Dipping killed all, or almost all, of the fungus in the soil adhering to the seed tubers.
The results are discussed and suggestions are made for further investigations and for practical control measures. 相似文献
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A white female with chronic glomerular nephritis received a renal transplant in 1971. After 1 year, Livido Reticularis (LR) developed and in 1976 erythematous, painful nodules formed on the LR and ulcerated. The patient also suffered diffuse calcification of the major blood vessels and small arterioles of the extremities with progressive necrosis and gangrene of the fingers. Hyperparathyroidism was evident. The necrotic ulcers yielded Candida albicans and Fusarium oxysporum; both organisms were seen in histological preparations. The ulcers were excised and grafted; no specific antifungal therapy was given. 相似文献
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Infection of mango panicles and young leaf shoots by Fusarium results in significantly lower fruit yields. Some mango cultivars are known to be tolerant to blossom malformation, while others are highly susceptible. Previous researchers linked the ability of certain cultivars to confine Fusarium infection to the production of high levels of mangiferin. This study further elucidates the role of phenolic metabolites contributing to tolerance. Phenolic profiles of mature leaf extracts from cultivars with varying degrees of resistance to Fusarium infection were obtained by ultrahigh performance liquid chromatography–time-of-flight-mass detection. Chemometric models constructed from the data revealed a clear distinction between the profiles of tolerant and susceptible cultivars and permitted the identification of biomarkers associated with susceptibility to infection. The presence of elevated levels of mangiferin, maclurin and maclurin O-galloyl-glucoside in the leaves were associated with a higher degree of tolerance. In contrast, high levels of iriflophenone glucosides were linked to increased susceptibility of the cultivars to infection. These models can serve as an important tool to investigate appropriate cultivars, prior to their introduction to areas prone to the disease. 相似文献